The Experts below are selected from a list of 1140 Experts worldwide ranked by ideXlab platform

D B Bogy - One of the best experts on this subject based on the ideXlab platform.

  • effect of the Hydrodynamic Bearing on rotor stator contact in a ring type ultrasonic motor
    IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 1992
    Co-Authors: Takashi Maeno, D B Bogy
    Abstract:

    A hybrid numerical analysis that includes the Hydrodynamic Bearing effect and elastic contact in a ring-type ultrasonic motor is presented. The two-dimensional time-dependent compressible Reynolds equation is solved numerically by a second-order time accurate, noniterative, factored implicit finite-difference algorithm. The rotor deformation is described by a one-dimensional Green's function. The contact problem is solved by an iteration method so that the contact condition and the Hydrodynamic Bearing condition are satisfied simultaneously. The results show that the Hydrodynamic Bearing effect, especially the squeeze effect, is significant for ultrasonic frequency contact of the rotor and stator. Surface roughness, contact area, and normal vibrating speed of the stator are important parameters in the Hydrodynamic Bearing. A disagreement between the friction coefficient needed in the numerical analysis and the experimentally measured one in a previous study. >

  • Effect of the Hydrodynamic Bearing on rotor/stator contact in a ring-type ultrasonic motor
    IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 1992
    Co-Authors: Takashi Maeno, D B Bogy
    Abstract:

    A hybrid numerical analysis that includes the Hydrodynamic Bearing effect and elastic contact in a ring-type ultrasonic motor is presented. The two-dimensional time-dependent compressible Reynolds equation is solved numerically by a second-order time accurate, noniterative, factored implicit finite-difference algorithm. The rotor deformation is described by a one-dimensional Green's function. The contact problem is solved by an iteration method so that the contact condition and the Hydrodynamic Bearing condition are satisfied simultaneously. The results show that the Hydrodynamic Bearing effect, especially the squeeze effect, is significant for ultrasonic frequency contact of the rotor and stator. Surface roughness, contact area, and normal vibrating speed of the stator are important parameters in the Hydrodynamic Bearing. A disagreement between the friction coefficient needed in the numerical analysis and the experimentally measured one in a previous study. >

  • effect of the Hydrodynamic Bearing on rotor stator contact in a ring type ultrasonic motor
    Internaltional Ultrasonics Symposium, 1991
    Co-Authors: Takashi Maeno, D B Bogy
    Abstract:

    A hybrid numerical analysis that includes the Hydrodynamic Bearing effect and elastic contact in a ring-type ultrasonic motor is presented. The two-dimensional Reynolds equation is solved numerically by a finite difference algorithm. The rotor deformation is described by a one-dimensional Green's function obtained by using a finite element elastic analysis code. The contact problem is solved by an iteration method so that the contact condition and the Hydrodynamic Bearing condition are satisfied simultaneously. The results show that the Hydrodynamic Bearing effect is significant for ultrasonic frequency contact of the rotor and stator. Surface roughness, contact area, and normal vibrating speed of the stator are important parameters in the Hydrodynamic Bearing. >

Takashi Maeno - One of the best experts on this subject based on the ideXlab platform.

  • effect of the Hydrodynamic Bearing on rotor stator contact in a ring type ultrasonic motor
    IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 1992
    Co-Authors: Takashi Maeno, D B Bogy
    Abstract:

    A hybrid numerical analysis that includes the Hydrodynamic Bearing effect and elastic contact in a ring-type ultrasonic motor is presented. The two-dimensional time-dependent compressible Reynolds equation is solved numerically by a second-order time accurate, noniterative, factored implicit finite-difference algorithm. The rotor deformation is described by a one-dimensional Green's function. The contact problem is solved by an iteration method so that the contact condition and the Hydrodynamic Bearing condition are satisfied simultaneously. The results show that the Hydrodynamic Bearing effect, especially the squeeze effect, is significant for ultrasonic frequency contact of the rotor and stator. Surface roughness, contact area, and normal vibrating speed of the stator are important parameters in the Hydrodynamic Bearing. A disagreement between the friction coefficient needed in the numerical analysis and the experimentally measured one in a previous study. >

  • Effect of the Hydrodynamic Bearing on rotor/stator contact in a ring-type ultrasonic motor
    IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 1992
    Co-Authors: Takashi Maeno, D B Bogy
    Abstract:

    A hybrid numerical analysis that includes the Hydrodynamic Bearing effect and elastic contact in a ring-type ultrasonic motor is presented. The two-dimensional time-dependent compressible Reynolds equation is solved numerically by a second-order time accurate, noniterative, factored implicit finite-difference algorithm. The rotor deformation is described by a one-dimensional Green's function. The contact problem is solved by an iteration method so that the contact condition and the Hydrodynamic Bearing condition are satisfied simultaneously. The results show that the Hydrodynamic Bearing effect, especially the squeeze effect, is significant for ultrasonic frequency contact of the rotor and stator. Surface roughness, contact area, and normal vibrating speed of the stator are important parameters in the Hydrodynamic Bearing. A disagreement between the friction coefficient needed in the numerical analysis and the experimentally measured one in a previous study. >

  • effect of the Hydrodynamic Bearing on rotor stator contact in a ring type ultrasonic motor
    Internaltional Ultrasonics Symposium, 1991
    Co-Authors: Takashi Maeno, D B Bogy
    Abstract:

    A hybrid numerical analysis that includes the Hydrodynamic Bearing effect and elastic contact in a ring-type ultrasonic motor is presented. The two-dimensional Reynolds equation is solved numerically by a finite difference algorithm. The rotor deformation is described by a one-dimensional Green's function obtained by using a finite element elastic analysis code. The contact problem is solved by an iteration method so that the contact condition and the Hydrodynamic Bearing condition are satisfied simultaneously. The results show that the Hydrodynamic Bearing effect is significant for ultrasonic frequency contact of the rotor and stator. Surface roughness, contact area, and normal vibrating speed of the stator are important parameters in the Hydrodynamic Bearing. >

Toru Masuzawa - One of the best experts on this subject based on the ideXlab platform.

  • axial magnetic Bearing development for the bivacor rotary bivad tah
    IEEE Transactions on Biomedical Engineering, 2010
    Co-Authors: Nicholas A. Greatrex, Nobuyuki Kurita, Daniel L. Timms, Edward Palmer, Toru Masuzawa
    Abstract:

    A suspension system for the BiVACOR biventricular assist device (BiVAD) has been developed and tested. The device features two semi-open centrifugal impellers mounted on a common rotating hub. Flow balancing is achieved through the movement of the rotor in the axial direction. The rotor is suspended in the pump casings by an active magnetic suspension system in the axial direction and a passive Hydrodynamic Bearing in the radial direction. This paper investigates the axial movement capacity of the magnetic Bearing system and the power consumption at various operating points. The force capacity of the passive Hydrodynamic Bearing is investigated using a viscous glycerol solution. Axial rotor movement in the range of ±0.15 mm is confirmed and power consumption is under 15.5 W. The journal Bearing is shown to stabilize the rotor in the radial direction at the required operating speed. Magnetic levitation is a viable suspension technique for the impeller of an artificial heart to improve device lifetime and reduce blood damage.

  • Axial magnetic Bearing development for the BiVACOR rotary BiVAD/TAH
    IEEE Transactions on Biomedical Engineering, 2010
    Co-Authors: Nicholas A. Greatrex, Edward W. Palmer, Nobuyuki Kurita, Daniel L. Timms, Toru Masuzawa
    Abstract:

    A suspension system for the BiVACOR biventricular assist device (BiVAD) has been developed and tested. The device features two semi-open centrifugal impellers mounted on a common rotating hub. Flow balancing is achieved through the movement of the rotor in the axial direction. The rotor is suspended in the pump casings by an active magnetic suspension system in the axial direction and a passive Hydrodynamic Bearing in the radial direction. This paper investigates the axial movement capacity of the magnetic Bearing system and the power consumption at various operating points. The force capacity of the passive Hydrodynamic Bearing is investigated using a viscous glycerol solution. Axial rotor movement in the range of +/-0.15 mm is confirmed and power consumption is under 15.5 W. The journal Bearing is shown to stabilize the rotor in the radial direction at the required operating speed. Magnetic levitation is a viable suspension technique for the impeller of an artificial heart to improve device lifetime and reduce blood damage.

G. H. Jang - One of the best experts on this subject based on the ideXlab platform.

  • Finite-element analysis of electromechanical field of a HDB spindle motor at elevated temperature
    IEEE Transactions on Magnetics, 2004
    Co-Authors: G. H. Jang, S J Park
    Abstract:

    This research presents a finite element method to analyze the electromechanical field of a Hydrodynamic-Bearing (HDB) spindle motor of computer hard disk drives at elevated temperature. Magnetic field is analyzed by the nonlinear time-stepping finite element method considering the switching action of PWM inverter, and magnetic force and torque are calculated by the Maxwell stress tensor. Mechanical motion of a rotor is determined by Newton's equation of motion, in which the Hydrodynamic Bearing force and friction torque are calculated by solving the Reynolds equation. Both the analyses of magnetic and mechanical field are combined in a closed loop to control the speed using PWM. Simulation results are verified by the experiments. This research also investigates the electromechanical performance of a HDB spindle motor at elevated operating temperature.

  • dynamic characteristics of a coupled journal and thrust Hydrodynamic Bearing in a hdd spindle system due to its groove location
    Microsystem Technologies-micro-and Nanosystems-information Storage and Processing Systems, 2002
    Co-Authors: G. H. Jang, J W Yoo
    Abstract:

    This research numerically analyzes the dynamic characteristics of a coupled journal and thrust Hydrodynamic Bearing due to its groove location which has the static load due to the weight of a rotor in the axial direction and the dynamic load due to its mass unbalance in the radial direction. The Reynolds equation is transformed to solve a plain member rotating type of journal Bearing (PMRJ), a grooved member rotating type of journal Bearing (GMRJ), a plain member rotating type of thrust Bearing (PMRT), and a grooved member rotating type of thrust Bearing (GMRT). FEM is used to solve the Reynolds equations in order to calculate the pressure distribution in a fluid film. Reaction forces and friction torque are obtained by integrating the pressure and shear stress along the fluid film, respectively. Dynamic behaviors, such as whirl radius or axial displacement of a rotor, are determined by solving its nonlinear equations of motion with the Runge–Kutta method. This research shows that the groove location affects the pressure distribution in the fluid film and consequently the dynamic performance of a HDD spindle system.

  • Calculation of dynamic coefficients in a Hydrodynamic Bearing considering five degrees of freedom for a general rotor-Bearing system
    ASME Journal of Tribology, 1999
    Co-Authors: G. H. Jang, Yong-jun Kim
    Abstract:

    A complete method is presented to calculate the stiffness and the damping coefficients in a Hydrodynamic Bearing considering five degrees of freedom for a general rotor-Bearing system. Perturbation equations are obtained from Reynolds equation by assuming the small amplitude motion of a Bearing center, and are solved by the finite element method. Their characteristics due to eccentricity and misalignment are investigated for herringbone groove journal and thrust Bearings in the spindle motor of a hard disk drive. This research shows that the dynamic coefficients increase with increasing the misalignment as well as the eccentricity due to the wedge effect. It also shows that the moment coefficients, which have been neglected in most of the previous analyses, are of significant magnitude in a journal Bearing and have even bigger values for the thrust Bearing when they are compared with the ball Bearing in the same type of a spindle motor.

Eiji Okamoto - One of the best experts on this subject based on the ideXlab platform.

  • A Hydrodynamically suspended, magnetically sealed mechanically noncontact axial flow blood pump: Design of a Hydrodynamic Bearing
    Artificial Organs, 2007
    Co-Authors: Yoshinori Mitamura, Kazuyuki Kido, Daisuke Sakota, Tetsuya Yano, Tomoyuki Yambe, Kazumitsu Sekine, Eiji Okamoto
    Abstract:

    To overcome the drive shaft seal and Bearing problem in rotary blood pumps, a Hydrodynamic Bearing, a magnetic fluid seal, and a brushless direct current (DC) motor were employed in an axial flow pump. This enabled contact-free rotation of the impeller without material wear. The axial flow pump consisted of a brushless DC motor, an impeller, and a guide vane. The motor rotor was directly connected to the impeller by a motor shaft. A Hydrodynamic Bearing was installed on the motor shaft. The motor and the Hydrodynamic Bearing were housed in a cylindrical casing and were waterproofed by a magnetic fluid seal, a mechanically noncontact seal. Impeller shaft displacement was measured using a laser sensor. Axial and radial displacements of the shaft were only a few micrometers for motor speed up to 8500 rpm. The shaft did not make contact with the Bearing housing. A flow of 5 L/min was obtained at 8000 rpm at a pressure difference of 100 mm Hg. In conclusion, the axial flow blood pump consisting of a Hydrodynamic Bearing, a magnetic fluid seal, and a brushless DC motor provided contact-free rotation of the impeller without material wear.